Adoptive transfer of cd8 +  t cell clones derived from central memory cells

ABSTRACT

The present invention provides a method of carrying out adoptive immunotherapy in a primate subject in need thereof by administering the subject a cytotoxic T lymphocytes (CTL) preparation in a treatment-effective amount. The method comprises administering as the CTL preparation a preparation consisting essentially of an in vitro expanded primate CTL population, the CTL population enriched prior to expansion for central memory T lymphocytes, and depleted prior to expansion of effector memory T lymphocytes. In some embodiments, the method may further comprise concurrently administering Interleukin-15 to the subject in an amount effective to increase the proliferation of the central memory T cells in the subject. Pharmaceutical formulations produced by the method, and methods of using the same, are also described.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 60/867,880, filed Nov. 30, 2007, the disclosure ofwhich is incorporated by reference herein in its entirety.

GOVERNMENT FUNDING

This invention was made with Government support under Grant NumbersR01CA114536, R01AI053193, CA18029, U01HL66947, and M01RR00037 from theNational Institutes of Health. The US Government has certain rights tothis invention.

FIELD OF THE INVENTION

The present invention concerns methods and compositions for carrying outadoptive immunotherapy.

BACKGROUND OF THE INVENTION

Studies in rodents have demonstrated that adoptive immunotherapy withantigen specific T cells is effective for cancer and infections, andthere is evidence this modality has therapeutic activity in humans¹⁻⁸.For clinical applications, it is necessary to isolate T cells of adesired antigen specificity or to engineer T cells to express receptorsthat target infected or transformed cells, and then expand these cellsin culture⁹⁻¹⁴. The transfer of T cell clones is appealing because itenables control of specificity and function, and facilitates evaluationof in vivo persistence, toxicity and efficacy. Additionally, in thesetting of allogeneic stem cell transplantation, the administration torecipients of T cell clones from the donor that target pathogens ormalignant cells can avoid graft-versus-host disease that occurs withinfusion of unselected donor T cells^(3,4,15). However, it is apparentfrom clinical studies that the efficacy of cultured T cells,particularly cloned CD8⁺ T cells, is frequently limited by their failureto persist after adoptive transfer^(16,17).

The pool of lymphocytes from which CD8⁺ T cells for adoptiveimmunotherapy can be derived contains naive and long-lived, antigenexperienced memory T cells (T_(M)). T_(M) can be divided further intosubsets of central memory (T_(CM)) and effector memory (T_(EM)) cellsthat differ in phenotype, homing properties and function's. CD8⁺ T_(CM)express CD62L and CCR7, which promote migration into lymph nodes, andproliferate rapidly if re-exposed to antigen. CD8⁺ T_(EM) lack CD62Lenabling migration to peripheral tissues, and exhibit immediate effectorfunction¹⁹.

In response to antigen stimulation, CD8⁺ T_(CM) and T_(EM) bothdifferentiate into cytolytic effector T cells (T_(E)) that express ahigh level of granzymes and perforin, but are short-lived²⁰. Thus, thepoor survival of T cells in clinical immunotherapy trials may simplyresult from their differentiation during in vitro culture to T_(E) thatare destined to die^(17,21,22).

SUMMARY OF THE INVENTION

A first aspect of the present invention is a method of carrying outadoptive immunotherapy in a primate subject in need thereof byadministering the subject a cytotoxic T lymphocytes (CTL) preparation ina treatment-effective amount. The method comprises administering as theCTL preparation a preparation consisting essentially of an in vitroexpanded (e.g., grown in vitro for 1, 2, or 3 days up to 3 or 4 weeks ormore) primate CTL population, the CTL population enriched prior toexpansion for central memory T lymphocytes, and depleted prior toexpansion of effector memory T lymphocytes. In some embodiments, themethod may further comprise concurrently administering Interleukin-15 tothe subject in an amount effective to increase the proliferation of thecentral memory T cells in the subject.

A further aspect of the invention is a pharmaceutical formulationcomprising, consisting essentially of or consisting of an in vitroexpanded primate cytotoxic T lymphocyte (CTL) population, the CTLpopulation enriched prior to expansion for central memory T lymphocytes,and depleted prior to expansion of effector memory T lymphocytes.

A further aspect of the invention is the use of a formulation asdescribed herein for the preparation of a medicament for carrying out amethod as described herein (e.g., treating cancer or an infectiousdisease in a human, or primate, subject).

In some embodiments the CTL preparation (or population) is produced bythe process of: (a) collecting a first CTL population from a donor; (b)separating a CTL subpopulation enriched for CD62L⁺ central memory Tlymphocytes and depleted of CD62L⁻ effector memory T lymphocytes toproduce a central memory-enriched CTL subpopulation; (c) expanding thecentral memory-enriched CTL subpopulation in vitro in a culture medium(e.g., for 1, 2, or 3 days up to 3 or 4 weeks or more); and then (d)collecting cells from the culture medium to produce the CTL preparation.The separating step “b” can in some embodiments be carried out by: (i)contacting the first CTL population to anti-CD62L antibody, wherein theantibody is immobilized on a solid support, so tht central memory cellsbind to the support; then (ii) separating the support from the CTLpopulation with central memory cells bound thereto; (iii) and thenseparating the central memory cells from the solid support to producethe central memory enriched CTL subpopulation. In some embodiments, theexpanding step “c” further comprises administering Interleukin-15 to thecentral memory subpopulation in vitro.

In some embodiments, the central memory-enriched T cells are modified invitro with at least one gene that targets (e.g., specifically binds to)cancer cells or other pathogenic cells in the subject.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. Isolation and genetic modification of CMV-specific CD8⁺ T cellclones from CD62L⁻ and CD62L⁺ T cell subsets for adoptive transfer.

FIG. 1 a. CMV IE-specific memory T cells are present in both CD62L⁺ andCD62L⁻ subsets of CD8⁺ peripheral blood lymphocytes. PBMC were sortedinto CD62L-CD8⁺ and CD62L⁺CD8⁺ fractions after staining with anti-CD8and anti-CD62L antibodies (upper panels). The CD62L⁻ and CD62L⁺fractions were stimulated for 6 hours with autologous CD40L-activated Bcells pulsed with medium alone or with CMV-IE peptide. Brefeldin A wasadded for the final 4 hours and CD8⁺ T cells that produced IFN-γ weredetected by staining for intracellular IFN-γ. The lower left panels showIFN-γ production by the CD62L⁻CD8⁺ subset and the lower right panelsshow IFN-γ production by the CD62L⁺CD8⁺ subset. Data from macaque 02269is shown and is representative of data obtained in four consecutivemacaques.

FIG. 1 b. Strategy for the isolation of CMV-specific CD8⁺ T cell clonesfrom CD62L⁻T_(EM) and CD62L⁺ T_(CM) subsets. Aliquots of PBMC wereobtained from each macaque and sorted into CD62L⁻CD8⁺ and CD62L⁺CD8⁻fractions after staining with anti-CD8 and anti-CD62L antibodies. Thesorted T cells were cultured with autologous monocytes pulsed with theCMV IE peptide and after 1 week of stimulation, T cells from thecultures were cloned by limiting dilution. T cell clones were screenedto identify those that lysed autologous peptide-pulsed target cells, andthen transduced with a retroviral vector that encoded a cell surfaceΔCD19 or CD20 molecule. Individual T cell clones were expanded in vitroto >5×10⁹ cells by stimulation with anti-CD3 and anti-CD28 antibodies incultures supplemented with γ-irradiated human PBMC and EBV-LCL prior toadoptive transfer.

FIG. 1 c. Retroviral vector constructs encoding for macaque cell surfacemarker genes. Abbreviations: MPSV-LTR, myeloproliferative sarcoma virusretroviral long terminal repeat; Ψ+, extended packaging signal; PRE,woodchuck hepatitis virus posttanscriptional regulatory element; ΔCD19,truncated macaque CD19 cDNA encoding the extracellular and transmembranedomains, and 4 aa of the cytosolic tail; CD20, full-length macaque CD20cDNA.

(d) Immunomagnetic bead selection of ΔCD19 and CD20-modified CD8⁺ T cellclones. Transduced T cells were enriched for ΔCD19 or CD20 expressingcells on day 8 after transduction using a two-step immunomagneticselection with anti-CD19 or anti-CD20 antibodies and rat anti-mouse IgGcoupled microbeads. Aliquots of unmodified (left panels) and ΔCD19 orCD20-modified T cells (right panels) were removed after selection,co-stained with anti-CD8 and anti-CD19 or anti-CD20 antibodies, andanalyzed by flow cytometry to assess purity. The percentages of CD8⁺ Tcells positive for the transgene are indicated.

FIG. 2. CMV-specific CD8⁺ T cell clones derived from T_(CM) and T_(EM)subsets exhibit an effector phenotype, and comparable avidity andproliferation in vitro.

FIG. 2 a. Individual T_(CM) and T_(EM)-derived macaque CMV-specific CD8⁺T cell clones were examined by flow cytometry for expression of CD62L,CCR7, CD28, CD127, granzyme B and perforin (bold line) and stained withisotype control antibodies (dotted line). Inset values represent themean fluorescence intensity (MFI). The data is shown for T cell clonesthat were adoptively transferred to macaque 02269 and is representativeof the data for all of the T cell clones used in adoptive transferexperiments in the three macaques.

FIG. 2 b. Cytotoxic activity of each pair of T_(EM) (filled triangle)and T_(CM) (filled square) -derived CMV-specific CD8⁺ T cell clones usedin adoptive transfer was examined in a 4-hour chromium release assay atan effector to target ratio of 20:1 using autologous target cells pulsedwith the CMV IE peptide at various concentrations. The sequences of theIE-1 peptides were KKGDIKDRV (02269) and EEHVKLFFK (A99171), thesequence of the IE-2 peptide was ATTRSLEYK (02258).

FIG. 2 c. In vitro growth of CMV-specific CD8⁺ T cell clones. The T_(EM)(filled triangle) and T_(CM) (filled square) derived T cell clones usedfor adoptive transfer were stimulated with anti-CD3 and anti-CD28 in thepresence of γ-irradiated feeder cells and IL-2 (50 U/ml). Cell growthover 14 days of culture was measured by counting viable cells usingtrypan blue exclusion.

FIG. 2 d. Telomere length in CMV-specific T cell clones derived fromCD62L⁺ and CD62L⁻ subsets. The median telomere length of duplicatesamples was measured by automated flow-FISH in peripheral blood Tlymphocytes (shaded squares), in the infused T cell clones (iT_(EM)filled squares, iT_(CM) open squares), and in each of two additionalrandomly selected T_(EM) (left hatched squares ) and T_(CM)-derived(right hatched squares ) T cell clones from each macaque.

FIG. 3. Persistence and migration of T_(EM) and T_(CM)-derived CD8⁺T_(E) clones in peripheral blood, bone marrow, and lymph nodes followingadoptive transfer.

FIGS. 3 a-b. In vivo persistence and migration of ΔCD19-modifiedT_(EM)-derived (a) and T_(CM)derived (b) T cell clones in macaque 02269.The T cell clones were transferred in separate infusions givenintravenously more than 10 weeks apart at a cell dose of 3×10⁸/kg.Samples of PBMC were collected at intervals for 6-8 weeks after eachinfusion. Bone marrow and lymph node samples were collected beforeinfusion and fourteen days after each T cell infusion. Samples werestained with fluorochrome-conjugated anti-CD3, CD8, and CD19 antibodies,respectively. The frequency of transferred CD19⁺ T cells was determinedby flow cytometry with gating on CD3⁺CD8⁺ cells. Left panels show thepercentage of CD8⁺ T cells that expressed CD19 in blood, bone marrow andlymph nodes prior to and at intervals after infusion of theT_(EM)-derived (a) and T_(CM)-derived (b) T cell clones. Right panelsshow the absolute numbers of CD19⁺CD3⁺CD8⁺ T cells per μl of blood. Thiswas determined by calculating the absolute number of CD3+CD8+ T cellsper μl of blood at the indicated days (% of CD3⁺CD8⁺ T cells in analiquot of mononuclear cells×mononuclear cell count per μl blood/100).Subsequently, the number of CD19⁺CD3⁺CD8⁺ T cells was derived (%CD19⁺CD3⁺CD8⁺ T cells x absolute CD3⁺CD8⁺ count per μl blood/100).

FIGS. 3 c-d. In vivo persistence and migration of adoptively transferredΔCD19-modified T_(CM) derived and CD20-modified T_(EM)-derived T cellclones in macaque 02258. CMV-specific CD8⁺ T cell clones were adoptivelytransferred in separate intravenous infusions at a cell dose of6×10⁸/kg. Aliquots of blood, bone marrow, and lymph nodes were obtainedbefore and at the indicated times after each T cell infusion andanalyzed by flow cytometry using specific antibodies to detect thetransferred CD19⁺CD8⁺ or CD20⁺CD8⁺ T cells, respectively. Left panelsshow the percentage of CD8⁺ T cells that expressed ΔCD19 (c) or CD20 (d)in blood, bone marrow and lymph nodes at intervals after each infusion.Right panels show the absolute number of CD3+CD8+T cells per μl of bloodthat expressed ΔCD19 (c) or CD20 (d) at intervals after infusion.

FIG. 4. T_(CM)-derived T_(E) clones undergo less apoptosis afteradoptive transfer compared with T_(EM)-derived T_(E) clones, and arerescued from cell death in vitro by IL-15.

FIG. 4 a. Expression of bcl-x1 and bcl-2 by T_(EM)-derived (opensquares) and T_(CM)-derived (filled squares) CD8⁺ T cell clonesadoptively transferred to macaques 02269, 02258, and A99171. The T cellswere analyzed at the end of a 14-day stimulation cycle by intracellularstaining with bcl-x1 and bcl-2 specific antibodies. The meanfluorescence intensity of staining is shown on the y axis.

FIG. 4 b. Apoptosis of T_(EM)-derived and T_(CM)-derived CD8⁺T_(E)clones in vivo. A ΔCD19-modified T cell clone derived from the CD62LT_(EM) fraction was adoptively transferred at a dose of 6×10⁸/kg tomacaque A99171, followed 5 weeks later by the infusion of the same celldose of a ΔCD19-modified T cell clone derived from the CD62L⁺ T_(CM)fraction. Samples of PBMC were obtained on day 1 after transfer and theproportion of ΔCD19-expressing CD8⁺ T cells that bound Annexin V and/orstained positive for PI was determined by flow cytometry after stainingwith anti-CD8 and CD19 antibodies, and with Annexin V and PI. PBMC wereanalyzed directly and after 24 hours of culture in CTL media. Theanalysis was performed after gating on CD8⁺CD19⁻ T cells (open squares)and on CD8⁺CD19⁺ T cells (filled squares), respectively. The hatchedbars show the proportion of T cells in each of the cell products priorto infusion that bound Annexin V or stained positive for PI.

FIG. 4 c. Persistence and migration of T_(EM)-derived and T_(CM)-derivedT^(E) clones in macaque A99171. Peripheral blood, bone marrow, and lymphnode cells obtained at intervals after each T cell infusion wereanalyzed by flow cytometry to detect transferred CD19⁺CD8⁺ T cells. Thesamples were analyzed after gating on CD3⁺CD8⁺ cells.

FIG. 4 d. IL-15 supports the in vitro survival of T_(CM)-derived but notT_(EM)-derived CD8+ T_(E) clones. Aliquots of the CMV-specificT_(EM)-derived and T_(CM)-derived CD8+ T cell clones that were used foradoptive transfer to macaques 02269, 02258, and A99171 respectively,were plated in wells containing medium alone (open triangles) or mediumsupplemented with IL-2 (16.6 U/ml; 1 ng/ml) (filled diamonds) or IL-15(1 ng/ml) (filled squares), respectively. The number of viable cells wasdetermined at the indicated days (up to 34 days) by counting cells usingtrypan dye exclusion.

FIG. 4 e. CD8⁺ T_(CM)-derived clones express higher levels of IL-15receptor (IL-15R) chains. Expression of IL-15Rα, IL-2Rβ, and IL-2Rγ onaliquots of CMV-specific T_(CM)-derived (bold line) and T_(EM)-derived(black line) T cell clones was measured by flow cytometry on day 13-14after stimulation. Staining with isotope control antibody is shown bythe dotted line. The data is shown for the T cell clones used for theadoptive transfer experiments in macaque 02269, and is representative ofthe data obtained for the T cell clones administered to macaques 02258and A99171, respectively.

FIG. 5. Adoptively transferred T_(CM)-derived T_(E) cells reacquiremarkers of T_(CM) in vivo and persist in memory cell niches.

FIG. 5 a. Expression of CD62L on T_(EM)-derived (upper panels) orT_(CM)-derived (lower panels) T_(E) clones after adoptive transfer.Samples of PBMC were obtained before and on day 3 after the infusion ofT_(CM) and T_(EM)-derived T cell clones, and analyzed by flow cytometryafter staining with fluorochrome-conjugated anti-CD3, CD8, CD62L, andeither CD19 or CD20 antibodies. Cells were gated to identify CD3⁺CD8⁺ Tcells and the percentage of T cells that expressed the CD19 or CD20marker gene and CD62L is shown in the upper right quadrant of eachpanel.

FIGS. 5 b-e. A major fraction of CD8⁺ T cells that persist afteradoptive transfer acquire phenotypic markers of T_(CM) and reside inlymph nodes. Aliquots of PBMC, lymph nodes (LN), and bone marrow (BM)were obtained from macaque 02258 at day 14 and day 56 after the infusionof the ΔCD19-modified T_(CM)-derived CMV-specific T cell clone. Theexpression of phenotypic markers of T_(CM) including CD62L (b), CCR7(c), CD28 (d), and CD127 (e) on the subset of transferred CD19⁺ T cellswas determined by flow cytometry after gating on CD3⁺CD8⁺ cells.

FIG. 6. Adoptively transferred CD8⁺ T cells that persist in vivo exhibitfunctional properties of memory T cells.

FIG. 6 a. Adoptively transferred CD8⁺ T cells that persist in vivoproduce IFN-γ after antigen stimulation. PBMC were obtained before the Tcell infusion (Pre) and 21 days after (Post) the infusion of aΔCD19-modified T_(CM)-derived CMV-specific CD8⁺ T cell clone. Aliquotsof PBMC were stimulated with medium alone, PMA/ionomycin, or the CMV LEpeptide recognized by the transferred T cell clone. IFN-γ production byCD8⁺ T cells was examined by cytokine flow cytometry after staining withanti-CD3, CD8, CD19, and IFN-γ antibodies. The analysis was performedafter gating on CD3⁺CD8⁺ T cells. The data is shown for macaque 02269and is representative of a separate experiment in macaque 02258.

FIG. 6 b. Adoptively transferred T cells that re-express CD62L lackdirect cytotoxicity but differentiate into cytotoxic cells after TCRstimulation. Left panel: PBMC obtained 14-70 days after the infusion ofa ΔCD19-modified T_(CM)-derived CD8⁺ T cell clone were pooled and sortedinto CD19⁺CD62L⁻CD8⁺ and CD19⁺CD62L⁺CD8⁺ fractions that were at least80% pure. The sorted cells were examined for recognition of autologoustarget cells alone (open squares) or pulsed with CMV IE peptide (closedsquares) in a 4-hour chromium release assay at an E/T ratio of 5:1. Thelysis of target cells by the in vitro cultured T_(CM)-derivedCD19-modified CD8⁺ T cell clone served as a positive control. Rightpanel: Aliquots of the sorted CD62L⁻ΔCD19⁺CD8⁺ and CD62L⁺ΔCD19⁺CD8⁺ Tcells were stimulated in vitro using anti-CD3 and CD28 antibodies, inthe presence of γ-irradiated feeder cells and IL-2 (50 U/ml). After 14days of culture, the cultures were assayed for recognition of peptidepulsed target cells in a 4-hour chromium release assay (E/T ratio of5:1). The data is shown for macaque 02258 and is representative of thatobserved with macaque 02269.

FIG. 6 c. Adoptively transferred T cells that reacquire CD62L in vivoexhibit more rapid proliferation than those that remain CD62L⁻. Aliquotsof the sorted ΔCD19⁺CD62L⁺CD8⁺ and ΔCD19⁺CD62L⁻CD8⁺ T cells from macaque02269 were labeled with CFSE (upper panels) and stimulated in vitro witheither CMV IE peptide-pulsed autologous CD40L activated B cells ormedium alone. After 5 days, dilution of CFSE was assessed by flowcytometry after gating on ΔCD19⁺CD3⁺CD8⁺ cells. The M3 gate identifiescells that have undergone more than five divisions.

FIG. 6 d. Adoptively transferred T cells can be driven to expand in vivoby the infusion of TAPC. Autologous T cells obtained and cryopreservedfrom macaque A99171 prior to any T cell infusions were thawed andexpanded by stimulation with anti-CD3 and anti-CD28 antibodies, andIL-2. After expansion, the T cells were pulsed with the CMV IE peptiderecognized by the adoptively transferred ΔCD19-modified T_(CM) clone.Eight weeks after the T cell infusion when a stable level of CD19⁺ Tcells was established in vivo, a dose of 1×10⁷ T-APC/kg was administeredintravenously. The absolute number of CD3⁺CD8⁻ T cells and CD19⁺CD8⁺ Tcells/μl of blood was measured on samples obtained prior toadministration of T-APC, and on day +3, +5 and +7 after the infusion ofT-APC. The number of endogenous IE-specific CD8⁺ T cells was measured atthe same time points by cytokine flow cytometry after gating onCD19⁻CD3⁺CD8⁺ cells. The data shows the fold-increase in the absolutenumbers of CD3⁺CD8⁺ T cells (open squares), CD19⁺CD8⁺ T cells (shadedsquares), and CD19⁻ IE-specific CD8⁺ T cells (filled squares) at day +3,+5 and +7 after the infusion of T-APC.

FIG. 6 e. T-APC pulsed with IE peptide are lysed by IE-specific CD8⁺ Tcells. T-APC generated from macaque A99171 either pulsed with IE peptide(filled squares) or with media alone (open squares) were labeled with⁵¹Cr and used as targets for an aliquot of the autologous IEspecificCD8⁺ T cell clone that was adoptively transferred to macaque A99171.

The present invention is explained in greater detail below. Thedisclosures of all United States patent references cited herein areincorporated by reference herein in their entirety.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

“T cells” or “T lymphocytes” as used herein may be from any mammalian,preferably primate, species, including monkeys, dogs, and humans. Insome embodiments the T cells are allogenic (from the same species butdifferent donor) as the recipient subject; in some embodiments the Tcells are autologous (the donor and the recipient are the same); in someembodiments the T cells are syngeneic (the donor and the recipients aredifferent but are identical twins).

Cytotoxic T lymphocyte (CTL) as used herein refers to a T lymphocytethat expresses CD8 on the surface thereof (i.e., a CD8⁺ T cell). In someembodiments such cells are preferably “memory” T cells (T_(M) cells)that are antigen-experienced. “Central memory” T cell (or “T_(CM)”) asused herein refers to a CTL that expresses CD62L on the surface thereof(i.e., CD62L⁺CD8⁺ cells).

“Effector memory” T cell (or “T_(EM)”) as used herein refers to a CTLthat does not express CD62L on the surface thereof (i.e., CD62L⁻CD8⁺cells).

“Enriched” and “depleted” as used herein to describe amounts of celltypes in a mixture refers to the subjecting of the mixture of the cellsto a process or step which results in an increase in the number of the“enriched” type and a decrease in the number of the “depleted” cells.Thus, depending upon the source of the original population of cellssubjected to the enriching process, a mixture or composition may contain60, 70, 80, 90, 85, or 99 percent or more (in number or count) of the“enriched” cells and 40, 30, 20, 10, 5 or 1 percent or less (in numberor count) of the “depleted” cells.

Interleukin-15 is a known and described in, for example, U.S. Pat. No.6,344,192.

I. In Vitro Expansion

T lymphocytes can be collected in accordance with known techniques andenriched or depleted by known techniques such as affinity binding toantibodies such as flow cytometry and/or affinity binding. Afterenrichment and/or depletion steps, in vitro expansion of the desired Tlymphocytes can be carried out in accordance with known techniques(including but not limited to those described in U.S. Pat. No. 6,040,177to Riddell et al.), or variations thereof that will be apparent to thoseskilled in the art.

For example, the desired T cell population or subpopulation may beexpanded by adding an initial T lymphocyte population to a culturemedium in vitro, and then adding to the culture medium feeder cells,such as non-dividing peripheral blood mononuclear cells (PBMC), (e.g.,such that the resulting population of cells contains at least about 5,10, 20, or 40 or more PBMC feeder cells for each T lymphocyte in theinitial population to be expanded); and incubating the culture (e.g. fora time sufficient to expand the numbers of T cells). The order ofadditional of the T cells and feeder cells to the culture media can bereversed if desired. The culture can typically be incubated underconditions of temperature and the like that are suitable for the growthof T lymphocytes. For the growth of human T lymphocytes, for example,the temperature will generally be at least about 25 degrees Celsius,preferably at least about 30 degrees, more preferably about 37 degrees.

The T lymphocytes expanded are typically cytotoxic T lymphocytes (CTL)that are specific for an antigen present on a human tumor or a pathogen.

The non-dividing feeder cells can comprise gamma-irradiated PBMC feedercells. In some embodiments, the PBMC are irradiated with gamma rays inthe range of about 3000 to 3600 rads.

Optionally, the expansion method may further comprise the step of addingnon-dividing EBV-transformed lymphoblastoid cells (LCL) as feeder cells.LCL can be irradiated with gamma rays in the range of about 6000 to10,000 rads. The LCL feeder cells may be provided in any suitableamount, such as a ratio of LCL feeder cells to initial T lymphocytes ofat least about 10:1.

Optionally, the expansion method may further comprise the step of addinganti-CD3 monoclonal antibody to the culture medium (e.g., at aconcentration of at least about 0.5 ng/ml). Optionally, the expansionmethod may further comprise the step of adding IL-2 and/or IL-15 to theculture medium (e.g., wherein the concentration of IL-2 is at leastabout 10 units/ml).

In some embodiments it may be desired to introduce functional genes intothe T cells to be used in immunotherapy in accordance with the presentinvention. For example, the introduced gene or genes may improve theefficacy of therapy by promoting the viability and/or function oftransferred T cells; or they may provide a genetic marker to permitselection and/or evaluation of in vivo survival or migration; or theymay incorporate functions that improve the safety of immunotherapy, forexample, by making the cell susceptible to negative selection in vivo asdescribed by Lupton S. D. et al., Mol. and Cell Biol., 11:6 (1991); andRiddell et al., Human Gene Therapy 3:319-338 (1992); see also thepublications of PCT/US91/08442 and PCT/US94/05601 by Lupton et al.,describing the use of bifunctional selectable fusion genes derived fromfusing a dominant positive selectable marker with a negative selectablemarker. This can be carried out in accordance with known techniques(see, e.g., U.S. Pat. No. 6,040,177 to Riddell et al. at columns 14-17)or variations thereof that will be apparent to those skilled in the artbased upon the present disclosure.

Various infection techniques have been developed which utilizerecombinant infectious virus particles for gene delivery. Thisrepresents a currently preferred approach to the transduction of Tlymphocytes of the present invention. The viral vectors which have beenused in this way include virus vectors derived from simian virus 40,adenoviruses, adeno-associated virus (AAV), and retroviruses. Thus, genetransfer and expression methods are numerous but essentially function tointroduce and express genetic material in mammalian cells. Several ofthe above techniques have been used to transduce hematopoietic orlymphoid cells, including calcium phosphate transfection, protoplastfusion, electroporation, and infection with recombinant adenovirus,adeno-associated virus and retrovirus vectors. Primary T lymphocyteshave been successfully transduced by electroporation and by retroviralinfection

Retroviral vectors provide a highly efficient method for gene transferinto eukaryotic cells. Moreover, retroviral integration takes place in acontrolled fashion and results in the stable integration of one or a fewcopies of the new genetic information per cell.

It is contemplated that overexpression of a stimulatory factor (forexample, a lymphokine or a cytokine) may be toxic to the treatedindividual. Therefore, it is within the scope of the invention toinclude gene segments that cause the T cells of the invention to besusceptible to negative selection in vivo. By “negative selection” ismeant that the infused cell can be eliminated as a result of a change inthe in vivo condition of the individual. The negative selectablephenotype may result from the insertion of a gene that conferssensitivity to an administered agent, for example, a compound. Negativeselectable genes are known in the art, and include, inter alia thefollowing: the Herpes simplex virus type I thymidine kinase (HSV-I TK)gene (Wigler et al., Cell 11:223, 1977) which confers ganciclovirsensitivity; the cellular hypoxanthine phosphribosyltransferase(HPRT)gene, the cellular adenine phosphoribosyltransferase (APRT) gene,bacterial cytosine deaminase, (Mullen et al., Proc. Natl. Acad. Sci.USA. 89:33 (1992)).

In some embodiments it may be useful to include in the T cells apositive marker that enables the selection of cells of the negativeselectable phenotype in vitro. The positive selectable marker may be agene which, upon being introduced into the host cell expresses adominant phenotype permitting positive selection of cells carrying thegene. Genes of this type are known in the art, and include, inter alia,hygromycin-B phosphotransferase gene (hph) which confers resistance tohygromycin B, the aminoglycoside phosphotransferase gene (neo or aph)from Tn5 which codes for resistance to the antibiotic G418, thedihydrofolate reductase (DHFR) gene, the adenosine daminase gene (ADA),and the multi-drug resistance (MDR) gene.

Preferably, the positive selectable marker and the negative selectableelement are linked such that loss of the negative selectable elementnecessarily also is accompanied by loss of the positive selectablemarker. Even more preferably, the positive and negative selectablemarkers are fused so that loss of one obligatorily leads to loss of theother. An example of a fused polynucleotide that yields as an expressionproduct a polypeptide that confers both the desired positive andnegative selection features described above is a hygromycinphosphotransferase thymidine kinase fusion gene (HyTK). Expression ofthis gene yields a polypeptide that confers hygromycin B resistance forpositive selection in vitro, and ganciclovir sensitivity for negativeselection in vivo. See Lupton S. D., et al, Mol. and Cell. Biology11:3374-3378, 1991. In addition, in preferred embodiments, thepolynucleotides of the invention encoding the chimeric receptors are inretroviral vectors containing the fused gene, particularly those thatconfer hygromycin B resistance for positive selection in vitro, andganciclovir sensitivity for negative selection in vivo, for example theHyTK retroviral vector described in Lupton, S. D. et al. (1991), supra.See also the publications of PCT/US91/08442 and PCT/US94/05601, by S. D.Lupton, describing the use of bifunctional selectable fusion genesderived from fusing a dominant positive selectable markers with negativeselectable markers.

Preferred positive selectable markers are derived from genes selectedfrom the group consisting of hph, neo, and gpt, and preferred negativeselectable markers are derived from genes selected from the groupconsisting of cytosine deaminase, HSV-I TK, VZV TK, HPRT, APRT and gpt.Especially preferred markers are bifunctional selectable fusion geneswherein the positive selectable marker is derived from hph or neo, andthe negative selectable marker is derived from cytosine deaminase or aTK gene.

A variety of methods can be employed for transducing T lymphocytes, asis well known in the art. For example, retroviral transductions can becarried out as follows: on day 1 after stimulation using REM asdescribed herein, provide the cells with 20-30 units/ml IL-2; on day 3,replace one half of the medium with retroviral supernatant preparedaccording to standard methods and then supplement the cultures with 5ug/ml polybrene and 20-30 units/ml IL-2; on day 4, wash the cells andplace them in fresh culture medium supplemented with 20-30 units/mlIL-2; on day 5, repeat the exposure to retrovirus; on day 6, place thecells in selective medium (containing, e.g., an antibiotic correspondingto an antiobiotic resistance gene provided in the retroviral vector)supplemented with 30 units/ml IL-2; on day 13, separate viable cellsfrom dead cells using Ficoll Hypaque density gradient separation andthen subclone the viable cells.

II. Compositions and Methods

Subjects that can be treated by the present invention are, in general,human and other primate subjects, such as monkeys and apes forveterinary medicine purposes. The subjects can be male or female and canbe any suitable age, including infant, juvenile, adolescent, adult, andgeriatric subjects.

Subjects that can be treated include subjects afflicted with cancer,including but not limited to colon, lung, liver, breast, prostate,ovarian, skin (including melanoma), bone, and brain cancer, etc. In someembodiments the tumor associated antigens are known, such as melanoma,breast cancer, squamous cell carcinoma, colon cancer, leukemia, myeloma,prostate cancer, etc. (in these embodiments memory T cells can beisolated or engineered by introducing the T cell receptor genes). Inother embodiments the tumor associated proteins can be targeted withgenetically modified T cells expressing an engineered immunoreceptor.Examples include but are not limited to B cell lymphoma, breast cancer,prostate cancer, and leukemia.

Subjects that can be treated also include subjects afflicted with, or atrisk of developing, an infectious disease, including but not limited toviral, retroviral, bacterial, and protozoal infections, etc.

Subjects that can be treated include immunodeficient patients afflictedwith a viral infection, including but not limited to Cytomegalovirus(CMV), Epstein-Barr virus (EBV), adenovirus, BK polyomavirus infectionsin transplant patients, etc.

Cells prepared as described above can be utilized in methods andcompositions for adoptive immunotherapy in accordance with knowntechniques, or variations thereof that will be apparent to those skilledin the art based on the instant disclosure. See, e.g., US PatentApplication Publication No. 2003/0170238 to Gruenberg et al; see alsoU.S. Pat. No. 4,690,915 to Rosenberg.

In some embodiments, the cells are formulated by first harvesting themfrom their culture medium, and then washing and concentrating the cellsin a medium and container system suitable for administration (a“pharmaceutically acceptable” carrier) in a treatment-effective amount.Suitable infusion medium can be any isotonic medium formulation,typically normal saline, Normosol R (Abbott) or Plasma-Lyte A (Baxter),but also 5% dextrose in water or Ringer's lactate can be utilized. Theinfusion medium can be supplemented with human serum albumen.

A treatment-effective amount of cells in the composition is at least10⁹, typically greater than 10⁹, at least 10¹⁰ cells, and generally morethan 10¹⁰. The number of cells will depend upon the ultimate use forwhich the composition is intended as will the type of cells includedtherein. For example, if cells that are specific for a particularantigen are desired, then the population will contain greater than 70%,generally greater than 80%, 85% and 90-95% of such cells. For usesprovided herein, the cells are generally in a volume of a liter or less,can be 500 mls or less, even 250 mls or 100 mls or less. Hence thedensity of the desired cells is typically greater than 10⁶ cells/ml andgenerally is greater than 10⁷ cells/ml, generally 10⁸ cells/ml orgreater. The clinically relevant number of immune cells can beapportioned into multiple infusions that cumulatively equal or exceed10⁹, 10¹⁰ or 10¹¹ cells.

In some embodiments, the lymphocytes of the invention may be used toconfer immunity to individuals. By “immunity” is meant a lessening ofone or more physical symptoms associated with a response to infection bya pathogen, or to a tumor, to which the lymphocyte response is directed.The amount of cells administered is usually in the range present innormal individuals with immunity to the pathogen. Thus, the cells areusually administered by infusion, with each infusion in a range of atleast 10⁶ to 10¹⁰ cells/m², preferably in the range of at least 10⁷ to10⁹ cells/m². The clones may be administered by a single infusion, or bymultiple infusions over a range of time. However, since differentindividuals are expected to vary in responsiveness, the type and amountof cells infused, as well as the number of infusions and the time rangeover which multiple infusions are given are determined by the attendingphysician, and can be determined by routine examination. The generationof sufficient levels of T lymphocytes (including cytotoxic T lymphocytesand/or helper T lymphocytes) is readily achievable using the rapidexpansion method of the present invention, as exemplified herein. See,e.g., U.S. Pat. No. 6,040,177 to Riddell et al. at column 17.

The present invention is illustrated further in the examples set forthbelow.

Experimental

In the normal host, T cell memory persists for life indicating thecapacity for selfrenewal in addition to differentiation²³. This qualityof T cell memory has been suggested to reside in the CD62L⁺ T_(CM)subset, although a unique subset of T cells that self-renew anddifferentiate has been identified in mice^(18,23,24). We sought todetermine if T_(E) clones differentiated in vitro from T_(CM) or T_(EM)subsets might differ intrinsically in their potential to persist afteradoptive transfer. Here, we show in a non-human primate model relevantfor human translation, that antigen-specific T_(E) clones derived fromT_(CM) but not T_(EM) precursors can persist, migrate to lymph nodes andbone marrow, reacquire phenotypic properties of T_(CM) and T_(EM), andrespond to antigen challenge.

Methods

Animals and experimental design. Adult macaques (Macaca nemestrina) werehoused at the University of Washington Regional Primate Research Center,under American Association for Accreditation of Laboratory Animal Careapproved conditions. The Institutional Animal Care and Use Committeeapproved the experimental protocols.

Healthy macaques were selected for this study if they had evidence ofprior CMV infection as determined by a positive lymphoproliferativeresponse to CMV antigen and a CD8⁺ T cell response to CMV IE-1 or IE-2peptides²⁵. CMV-specific CD8⁺ T cell clones were isolated fromCD62L⁺CD8⁺ and CD62L⁻CD8⁺ T cells obtained by cell sorting of PBMC fromeach macaque, modified by retroviral gene transfer, expanded in vitroand infused intravenously at cell doses of 3-6×10⁸/kg. Blood sampleswere obtained by venipuncture at intervals after each infusion and bonemarrow from the posterior iliac crest and a lymph node from the inguinalregion were obtained under anaesthesia.

Accredited clinical laboratories performed CBC and serum chemistry onblood obtained before and at intervals after each T cell infusion. Themacaques were followed for at least 7 weeks after each T cell infusion.

Cytokine flow cytometry for detection of CMV-specific CD8⁺ T cells. PBMCwere isolated from peripheral blood by Ficoll-Hypaque gradientseparation. Multiparameter flow cytometry was used to detect CD8⁺ Tcells in PBMC that expressed intracellular IFN-γ after stimulation withpools of 15-mer synthetic peptides with an 11 amino acid (aa) overlapthat spanned the 558 aa sequence of the rhCMV IE1 protein (GenBankaccession number: M93360), or with an IE-2 peptide kindly provided byDr. L. Picker (Oregon Health Sciences University)²⁵. The peptides thatcomprised the panel were synthesized using standard FMOC chemistry (NMI)and arranged in an analytic grid composed of 24 pools, each containing11-12 peptides. Aliquots of PBMC were stimulated for 6 hours at 37° C.with the peptide pools (5 μg/ml) or medium alone in the presence of 1μg/ml monoclonal anti-CD28 and anti-CD49d antibodies. Stimulation withPMA (10 ng/ml; Sigma) and ionomycin (1 μg/ml; Sigma) was performed as apositive control. After two hours, Brefeldin A (10 μg/ml; Sigma) wasadded. The cells were first stained with phycoerythrin (PE)-labeledanti-CD8β (Immunotech Coulter) and peridinin chlorophyll protein(Percp)-Cy5.5-labeled anti-CD4, then permeabilized usingCytofix/Cytoperm Permeabilization Solution (BD Biosciences (BD)), andstained with a fluorescein isothiocyanate (FITC)-labeled anti-IFN-γantibody (BD). All analyses were performed on a FACSCalibur and the dataanalyzed using CellQuest Software (BD). Immunogenic CMV peptides wereidentified by the responses of CD8⁺ T cells to intersecting peptides inthe grid and the assays were repeated with each individual peptide andderivative 9-mer peptides to confirm and map specificity.

To determine if CD8⁺ T cells for CMV IE peptides were present in theT_(CM) and T_(EM) subsets, PBMC were stained with fluorochromeconjugated anti-CD8 and anti-CD62L monoclonal antibodies, and CD62L⁺CD8⁺T cells and CD62L⁻CD8⁺ T cells were sorted using a Vantage BD cellsorter. The sorted cells were assayed by cytokine flow cytometry afterstimulation with autologous B cells that were activated by culture onNIH 3T3 cells modified to express human CD40L, and then pulsed withindividual IE peptides or with media alone. The CD40L-activated B cellswere cocultured with the purified CD62L⁺CD8⁺ and CD62L⁻CD8⁺ T cells for6 hours prior to the addition of Brefeldin A for an additional 4 hours,followed by permeabilization and staining for intracellular IFN-γ.

Retroviral vectors. A truncated macaque CD19 gene encoding for theextracellular and transmembrane domain (ΔCD19) and four aa of thecytoplasmic tail to abrogate signaling, and the full length CD20 genewere amplified by RT-PCR from cDNA generated from macaque PBMC andcloned into pcDNA3.1 vector (Invitrogen). The ΔCD19 and CD20 genes weresubcloned into the retroviral plasmid pMP71GFP_(pre) (W. Uckert,Max-Delbrück-Center, Berlin, Germany) after removing the GFP gene⁴³.Retrovirus supernatant was produced in the packaging cell line PhoenixGalv (G. Nolan, Stanford University, USA) after transfection usingFugene G according to the manufacturer's instruction (RocheDiagnostics).

Culture and genetic modification of CMV-specific CD8⁺ T cell clones foradoptive transfer. CD62L⁻CD8⁺ and CD62L⁻CD8⁺ T cell fractions wereresuspended in RPMI 1640 supplemented with 25 mM HEPES, 10% human ABserum, 25 μM 2-mercaptoethanol, and 4 mM L-glutamine (T-cell media), andco-cultured with autologous monocytes pulsed with CMV IE-1 or IE-2peptides (1 μg/ml). IL-2 (10 U/ml; Chiron Corporation) was added on day3 of the culture. On day 7, T cell clones were generated by plating 0.3T cells per well in 96-well round bottom plates with 1×10⁵ γ-irradiatedautologous PBMC pulsed with CMV IE-1 or IE-2 peptides (0.5 μg/ml) and1×10⁴ irradiated B-lymphoblastoid cells (LCL) as feeder cells in thepresence of 50 U/ml IL-2.

After 14 days, an aliquot from cloning wells with visible growth wastested in a chromium release assay for recognition of autologous targetcells either pulsed with CMV peptide or with medium alone. T cell clonesthat only lysed peptide pulsed target cells were expanded by stimulationwith monoclonal anti-CD3 and anti-CD28 antibodies in the presence ofhuman γ-irradiated PBMC and EBV transformed LCL, and IL-2 (50 U/ml) asdescribed^(44,45). On day 2 after stimulation, the cells were pelleted,resuspended in ΔCD19 or CD20 retroviral supernatant with IL-2 (50 U/ml)and polybrene (5 μg/ml), centrifuged at 1000 g for 1 hour at 32° C., andincubated overnight. The cells were then washed and cultured in CTLmedium containing IL-2. On day 6 after retroviral transduction, T cellsthat expressed the ΔCD19 or CD20 transgene were selected withimmunomagnetic beads. Briefly, the transduced T cells were incubatedwith monoclonal anti-CD19 (Immunotech Coulter) or anti-CD20 antibody(BD), washed, incubated with rat anti-mouse IgG-coupled magnetic beads(Miltenyi Biotec), and selected using the MidiMACS device. The selectedcells were then cultured for an additional 6 days and cryopreserved inaliquots that could be thawed subsequently for adoptive transferexperiments. The clonality of the infused T cell clones was confirmed byanalysis of TCR Vβ gene rearrangements.

To assess cell viability in vitro, aliquots of the T cell clones at theend of the 14-day stimulation cycle and immediately prior to adoptivetransfer were plated in 12-well tissue culture plates at 2-4. 10⁶cells/well in T-cell media alone, media with IL-2 (1 ng/ml or 16 U/ml;Chiron), IL-15 (1 ng/ml; R&D Systems), or IL-7 (10 ng/ml; R&D).

The viability of T cells was assessed every 3-4 days by trypan blue dyeexclusion. In some experiments, aliquots of the T cell clones werecultured with media containing IL19 21 (30 ng/ml) (R&D) or coculturedwith autologous PBMC and mature monocytederived dendritic cells⁴⁶.

Generation of T-APC. To generate T-APC, we expanded aliquots ofautologous polyclonal T cells by stimulation with anti-CD3 and anti-CD28monoclonal antibodies and IL-2 (50 U/ml). At the end of a 14 daystimulation cycle, the T cells were harvested, pulsed for 30 min with 1μg/ml of the cognate CMV IE peptide, washed twice in media, suspended innormal saline and administered to the animal by intravenous infusion ata cell dose of 1×10⁷/kg. An aliquot of the autologous T cells before andafter pulsing with the CMV IE peptide were labeled with ⁵¹Cr and testedas targets for the CMV-specific T cell clone.

Cytotoxicity assays. Cytotoxic responses of CMV-specific T cells wereexamined as described^(44,45,47). Briefly, autologous ⁵¹Cr-labeled Tcells were pulsed overnight with peptide antigen at variousconcentrations or medium alone and used in a chromium release assay forrecognition by CD8⁺ T cell clones.

Flow cytometry. PBMC and T cell clones were analyzed by flow cytometryafter staining with fluorochrome-conjugated monoclonal anti-CD3 (SP34),CD4, CD8, CD27, CD28, CD45RA, CD62L, CCR7, CD122 (IL2-Rβ), CD132(IL2-R-γ) (BD), CD19, CD80, CD45RO, and CD127 (Immunotech Coulter), andIL15R((R&D) antibodies. For intracellular staining, cells were suspendedin CYTOFIX/CYTOPERM™ Permeabilization Solution (BD) according to themanufacturer's instruction and stained with monoclonal antibodies togranzyme B (BD), perforin (Kamiya Biomedical), bcl-2 (BD), and bcl-x1(Southern Biotech). Isotype-matched irrelevant control monoclonalantibodies served as controls (BD). In some experiments, samples of PBMCwere labeled with anti-CD8-FITC and anti-CD19 allophycocyanin (APC) andstained with Annexin V-PE and PI according to the manufacturer'sinstruction. All analyses were performed on a FACSCalibur and the dataanalyzed using CellQuest Software (BD).

CFSE-labeling of T cells. CD19⁺CD62L⁺CD8⁺ and CD19⁺CD62L⁻CD8⁺ T cellswere flow sorted from pooled PBMC samples obtained after adoptivetransfer and labeled with 0.625 μM CFSE (Molecular Probes) in PBS for 10minutes at 37° C. under constant agitation, followed by blocking with20% FCS medium. CFSE-labeled T cells were plated at 1×10⁵ cells/well ina 96-well plate with autologous CD40L activated B cells (2.5×10⁴cells/well) pulsed with 200 ng/ml CMV IE peptide. CFSE dilution wasanalyzed by flow cytometry after five days.

Fluorescent Probe PCR. PCR amplifications and analyses were performedusing a quantitative real-time PCR assay (Perkin-Elmer AppliedBiosystems)^(45,48), DNA (0.3-1 μg) was amplified in duplicate using PCRprimers and TaqMan probes (Synthegen) designed to detect a uniqueMP71CD20_(pre) sequence using a fluorescent-tagged probe encompassingthe junction of the CD20 gene and the retroviral vector pMP71_(pre).

Standards consisted of DNA derived from the infused CD20+ T cells.Aliquots of preinfusion PBMC served as negative control.

Telomere length analysis. The average length of telomere repeats inindividual lymphocytes was measured by automated flow-FISH asdescribed^(49,50.). Cells, which were previously frozen in 10% (v/v)DMSO 20% (v/v) human serum, were thawed and processed in microtiterplates for automated flow-FISH. Cells were hybridized with or without0.3 μg/ml telomere specific FITC-conjugated (CCCTAA)₃ PNA probe, washedand counterstained with 0.01 μg/ml LDS 751 (Exciton Chemical). Toconvert the fluorescence measured in sample cells hybridized with theFITC-labeled telomere PNA probe into kilobases (kb) of telomere repeats,fixed bovine thymocytes with known telomere length as an internalcontrol were processed simultaneously with each sample⁵⁰. FITC-labeledfluorescent beads were used to correct for daily shifts in the linearityof the flow cytometer and fluctuations in the laser intensity andalignment. Flow cytometric data collection was performed on aFACSCalibur™ apparatus and the data analysis was performed using aCellQuestPro™ data analysis system (BD).

Results

Characterization of Cytomegalovirus (CMV)-specific CD8⁺ T cell clonesderived from CD62L⁺ T_(CM) and CD62L⁻ T_(EM) subsets. ImmunocompetentMacaca nemestrina with latent CMV infection were used in this study. Toidentify CMV-specific CD8⁺ T cells, we stimulated aliquots of peripheralblood mononuclear cells (PBMC) from four macaques with rhesus CMVimmediate early (IE)-1 or IE-2 peptides and analyzed interferon-gamma(IFN-γ) production by flow cytometry²⁵. After identification of animmunogenic CMV epitope for each macaque, we evaluated whether specificCD8⁺ T cells were present in CD62L+and CD62L⁻ T cell fractions, purifiedfrom PBMC and containing T_(CM) and T_(EM) respectively. Stimulation ofCD62L⁺ and CD62L⁻ T cells with CMV peptides identified CD8⁺ T cells thatproduced IFN-γ in both subsets (FIG. 1 a). The majority of CD62L⁺ Tcells were positive for CCR7 and CD28, and expressed absent or lowlevels of granzyme B. The CD62L⁻ T cells were mostly negative for CD28and CCR7, and positive for granzyme B (not shown).

We next generated CD8⁺CMV-specific T cell clones for adoptive transferfrom purified CD62L⁺CD8⁺ (T_(CM)) and CD62L⁻CD8⁺ (T_(EM)) cells of threemacaques (FIG. 1 b). Cytolytic CD8⁺CMV-specific T cell clones wereobtained from both T_(M) subsets in all macaques. The cloning efficiencywas 13.6-23.2% for cultures initiated from T_(CM), and 0.4-10.4% forcultures initiated from T_(EM). Individual T cell clones were transducedwith a retroviral vector encoding either a truncated cell surface CD19(ΔCD19) or full-length CD20 molecule to permit tracking the cells invivo, and transduced T cells were selected with immunomagnetic beads(FIGS. 1 c, d). A pair of T_(CM) and T_(EM)-derived clones was randomlyselected from each of the three macaques, and expanded in culture to>5×10⁹ cells over a total culture duration of 49 days before adoptivetransfer. Independent of their derivation from CD62L⁺ or CD62L⁻ cells,all of the CMV-specific T cell clones had differentiated to T_(E) andwere negative for CD62L, CCR7, CD28, and CD127, and positive forgranzyme B and perforin (FIG. 2 a). The T cell clones of each pairrecognized the same CMV peptide, had comparable avidity, displayednearly identical growth after T cell receptor (TCR) stimulation, and hadsimilar telomere lengths (FIGS. 2 b-d).

In vivo persistence of CD8⁺ T_(E) clones derived from CD62L⁺ T_(CM) orCD62L⁻ T_(EM). We administered the autologous gene-modified T cellsintravenously and measured their frequency in the blood, lymph node, andbone marrow at intervals after infusion. A ΔCD19-modified T cell clonederived from T_(EM) was transferred to macaque 02269 at a dose of 3×10⁸T cells/kg, which is approximately 5-10% of the macaque total bodylymphocyte pool²⁶. CD19⁺CD8⁺ T cells were easily detected in the bloodone day after the infusion at a frequency of 1.2% of CD8⁺ cells or 10cells/μl of blood. The CD19⁺T cells in the blood peaked at 3.7% of CD8⁺T cells (40 cells/μl) on day three after the infusion. However, the Tcells were not detected in blood obtained at day five or multiple timesup to forty-two days after infusion, and were not present in bone marrowor lymph node samples obtained fourteen days after the infusion (FIG. 3a). We transferred the same dose of a ΔCD19-modified CMV-specific T cellclone derived from the T_(CM) subset to this macaque. On day one postinfusion, the frequency of CD19⁺CD8⁺ T cells in the blood was 2.2% ofCD8⁺ T cells (10 cells/μl). In contrast to the T_(EM)-derived clone, theT_(CM)-derived cells persisted in the blood for greater than fifty-sixdays after infusion at ˜0.2% of CD8⁺ T cells (3-6 cells/μl), andcomprised 1.2% and 0.6% of CD8⁺ T cells in bone marrow and lymph nodesamples respectively, obtained fourteen days after the infusion (FIG. 3b). In a second macaque, we infused a ΔCD19-modified T_(CM)-derivedclone first at a higher cell dose of 6×10⁸/kg. With this dose,transferred cells were detected in the blood at a frequency of 26.3% ofCD8⁺ T cells (228 cells/μl) on day one and 46.3% of CD8⁺ T cells (734cells/μl) on day three. The transferred T_(CM)-derived clone was presentin the bone marrow and lymph node obtained on day fourteen at 4.7% and0.7% of CD8⁺ T cells, respectively (FIG. 3 c). The frequency of thetransferred cells in the blood declined gradually over twenty-eight daysto a stable level of 7-10 cells/μl that persisted for greater thaneleven months after infusion (FIG. 3 c). We administered the same doseof a T_(EM)-derived clone transduced to express CD20 to enable the cellsto be tracked and distinguished from the previously transferredΔCD19-modified T cells. The frequency of CD20⁺CD8⁺ T cells in the bloodone day after the infusion was 16.3% of CD8⁺ T cells (103 cells/μl), butthe transferred cells disappeared from the blood by day five and werenot detected in the bone marrow and lymph node obtained fourteen daysafter the infusion (FIG. 3 d). The disappearance of CD20-modified Tcells was confirmed by PCR for vector sequences on DNA isolated fromperipheral blood, bone marrow and lymph node mononuclear cells obtainedon day 14 (data not shown).

CD8⁺ T_(E) cells derived from T_(EM) undergo rapid apoptosis afteradoptive transfer and respond poorly to IL-15. The failure of T_(E)clones derived from T_(EM) to persist in blood, marrow or lymph nodesafter adoptive transfer could be due to cell death in vivo and/ormigration to other tissue sites. T_(EM)-derived clones expressed lowerlevels of the anti-apoptotic proteins bclx1 and bcl-2 thanT_(CM)-derived clones, suggesting they may be more susceptible toapoptosis (FIG. 4 a). Therefore, we infused a ΔCD19-modifiedT_(EM)-derived T cell clone to the third macaque and measured theproportion of transferred cells in PBMC that were positive for propidiumiodide (PI) and Annexin V binding²⁷. Approximately 40% of the CD19⁺CD8⁺T cells in PBMC were PI and/or Annexin V positive when analyzed directlyon day one, and 45% were positive after culturing the PBMC for 24 hours(FIG. 4 b).

Consistent with the prior animals, the T_(EM)-derived clone was onlydetected in the blood for three days, and was not present in the dayfourteen bone marrow or lymph node samples (FIG. 4 c). We then infused aΔCD19-modified T_(CM)-derived T cell clone into the same animal andanalyzed the proportion of apoptotic cells. Less than 20% of thetransferred T_(CM) cells were PI and/or Annexin V positive in PBMCanalyzed directly, and this fraction decreased to 12% after 24 hours ofculture (FIG. 4 b). The T_(CM)-derived clone migrated to the bone marrowand lymph nodes (FIG. 4 c), and persisted in the blood for greater thanseventy-seven days as observed previously (data not shown). We reasonedthat the selective survival of T_(CM)-derived T cells in vivo might bedue to responsiveness to homeostatic cytokines such as IL-15 thatmaintain endogenous CD8⁺ memory T cells²⁸⁻³⁰, and cultured aliquots ofthe T_(CM) and T_(EM)-derived clones in media containing low doses ofIL-15, IL-2, or IL-7. Both T_(EM) and T_(CM)-derived T_(E) _(E) cloneslacked expression of IL-7Rα (FIG. 2 a) and died rapidly in vitro whencultured in IL-7 or in media alone (FIG. 4 d). Culture in IL-15 or IL-2also did not improve the viability of T_(EM)-derived clones (FIG. 4 d).By contrast, T_(CM)-derived clones were rescued from cell death for over30 days in IL-15 and exhibited improved survival in IL-2 (FIG. 4 d). Theresponsiveness of T_(CM)-derived clones to IL-15 correlated with higherlevels of cell surface IL-15Rα, IL-2Rβ®, and IL-2Rγ compared withT_(EM)-derived clones (FIG. 4 e).

Adoptively transferred CD8⁺ T_(E) clones derived from T_(CM) acquire amemory phenotype in vivo. The migration of T_(CM)-derived CD8⁺ T_(E)clones to lymph nodes suggested that CD62L might be re-expressed ontransferred cells in vivo. CD62L was not detected on the T cell clonesat the time of adoptive transfer (FIG. 2 a), or after culture in theabsence of antigen stimulation with cytokines (IL-2, IL-7, IL-15,IL-21), autologous PBMC, or monocyte-derived dendritic cells (data notshown). However, in all three macaques, CD19⁺CD62L⁺CD8⁺ cells wereobserved in the blood as early as three days after the infusion of theT_(CM)-derived clones and were detected in the blood, bone marrow andlymph node samples obtained on day 14 (FIG. 5 a, b). The proportion oftransferred T cells that were CD62L⁺ in the lymph node was greater thanin blood or marrow (FIG. 5 b).

CD62L was not expressed during the brief period the T_(EM)-derived clonepersisted in the blood in any of the three macaques (FIG. 5 a). We nextexamined whether the T cells that persisted in vivo after adoptivetransfer acquired other phenotypic markers of memory T cells that wereabsent on the infused T_(E). Fourteen days after cell transfer, a subsetof the CD19⁺CD8⁺ T cells in blood and lymph node expressed CCR7, CD28,and CD127 (FIGS. 5 c-e). We repeated this analysis on blood, bonemarrow, and lymph node samples obtained two months after the infusion ofthe T_(CM)-derived clone in macaque 02258. At this later time, theinfused CD19⁺T cells comprised 1.4% of the CD8⁺ T cells in the lymphnode and these T cells were uniformly positive for T_(CM) markersincluding CD62L, CCR7, CD28, and CD127 (FIGS. 5 b-e). Transferred Tcells were present at lower levels in the blood and bone marrow, andcontained both CD62L⁺ and CD62L⁻ fractions. The transferred CD19⁺T cellsthat persisted long-term in the blood and expressed CD62L, alsoexpressed CR7, CD28 and CD127 (not shown). Thus, despite differentiationto T_(E) during expansion of a single T_(CM) cell to more than 5×10⁹cells, a significant fraction of the transferred T cell clones were ableto persist long-term, compete with endogenous T cells for anatomicalniches of T_(CM), and re-express phenotypic markers of T_(CM).

Memory T cells established by adoptive transfer exhibit functionalproperties of both T_(CM) and T_(EM). An objective of T cellimmunotherapy is to establish a stable pool of memory T cells that canrespond to antigen by producing cytokines and differentiating intocytolytic effector cells. The transferred CD19⁺T_(CM)-derived cells thatpersisted in the blood produced IFN-γ after peptide stimulation andtheir frequency was comparable to endogenous CD19⁻ CMV-specific CD8⁺ Tcells (FIG. 6 a). The cytolytic function of these T cells was examinedby sorting T cells from the blood into CD19⁺CD62L⁺CD8⁺ andCD19^(+CD)62L⁻CD8⁺ fractions. For these experiments, it was necessary topool PBMC samples from multiple time points to obtain sufficient cellsfor the assays. The CD19⁺CD62L⁻ T cells demonstrated cytolytic activitynearly equivalent to that of the T cell clone and expressed granzyme B,while the CD19⁺CD62L⁺ T cells lacked direct cytolytic activity and hadlow granzyme B expression (FIG. 6 b). In vitro stimulation of theCD19⁺CD62L⁺ T cells with anti-CD3 and anti-CD28 monoclonal antibodiesgenerated T_(E) cells with cytolytic activity, demonstrating these cellscould be re-induced to differentiate to cytolytic T_(E) (FIG. 6 b). Wealso labeled the sorted CD19⁺CD62L⁺ and CD19⁺CD62L⁻ T cell fractionswith CFSE and monitored proliferation five days after antigenstimulation in vitro. Seventy-four percent of CD62L⁺ cells underwent 5or more cell divisions, but only 13% of CD62L⁻ cells underwent 5 or moredivisions (FIG. 6 c). Thus, the adoptive transfer of a T_(E) clonederived from the T_(CM) pool established distinct populations of cellsin vivo with the functional properties of T_(CM) and T_(EM).

We have previously shown in human studies that the infusion of T cellsthat express a foreign antigen can prime and boost endogenousantigen-specific memory T cell responses³¹. Thus, to determine if T_(M)established by adoptive transfer could respond to antigen stimulation invivo, we infused a small dose (1×10⁷/kg) of autologous T cells pulsedwith CMV IE peptide (T-APC) into macaque A99171 two months afteradministering the ΔCD19-modified T_(CM)-derived T cells. The peptidepulsed T-APC were efficiently lysed by the CMV-specific T cell clone invitro (FIG. 6 e). Within 7 days of the infusion of T-APC, there was a 4to 5-fold increase in the absolute numbers of both ΔCD19-modified andendogenous IE-specific T cells in the blood (FIG. 6 d). Thus, the memoryT cells established by adoptive transfer were as capable as endogenousmemory T cells of expanding in response to antigen in vivo.

Discussion

Poor survival of adoptively transferred T cells that target infected orcancerous cells has correlated with lack of therapeutic efficacy inclinical trials^(14,16,16). The persistence and efficacy of cultured Tcells can sometimes be improved by depletion of host lymphocytes priorto cell transfer to eliminate regulatory cells and competition forpro-survival cytokines, and by the administration of IL-2 after celltransfer^(16,17). However, these interventions are not uniformlysuccessful in improving cell persistence suggesting that intrinsicproperties of T cells isolated for adoptive therapy may be critical forestablishing durable immunity. Here, we used gene marking to show thatantigen-specific CD8⁺ T_(E) clones derived in vitro from the T_(CM) butnot from the T_(EM) subset, persist longterm in vivo, occupy memory Tcell niches, and reacquire phenotypic and functional properties ofT_(CM) after adoptive transfer.

After encountering antigen in vivo, T cells undergo proliferation andprogrammed differentiation evoked by signals from the TCR,co-stimulatory and adhesion molecules, and cytokinereceptors^(18,20,32). These events result in the generation of largenumbers of T_(E) that die as antigen is cleared, and a smaller pool ofphenotypically distinct T_(CM) and T_(EM) that persist for life andrespond to antigen re-exposure by differentiating into T_(E). Data fromboth murine and human studies support a linear differentiation model inwhich T_(CM) give rise to both T_(EM) and T_(E), although it remainspossible that T_(CM) and T_(EM) represent separate lineages^(18,33-35).The capacity of T cell memory to be maintained for life suggests that atleast some T_(M) must be capable of both self-renewal anddifferentiation²³.

The results presented here suggest that isolating T_(CM) for geneinsertion may provide a tumor-reactive T cell population with animproved capacity to persist after adoptive transfer.

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The foregoing is illustrative of the present invention, and is not to beconstrued as limiting thereof. The invention is defined by the followingclaims, with equivalents of the claims to be included therein.

1. In a method of carrying out adoptive immunotherapy in a primatesubject in need thereof by administering said subject a cytotoxic Tlymphocytes (CTL) preparation in a treatment-effective amount, theimprovement comprising: administering as said CTL preparation apreparation consisting essentially of an in vitro expanded primate CTLpopulation, said CTL population enriched prior to expansion for centralmemory T lymphocytes, and depleted prior to expansion of effector memoryT lymphocytes.
 2. The method of claim 1, wherein said CTL preparation isproduced by the process of: (a) collecting a first CTL population from adonor; (b) separating a CTL subpopulation enriched for CD62L⁺ centralmemory T lymphocytes and depleted of CD62L⁻ effector memory Tlymphocytes to produce a central memory-enriched CTL subpopulation; (c)expanding said central memory-enriched CTL subpopulation in vitro in aculture medium; and then (d) collecting cells from said culture mediumto produce said CTL preparation.
 3. The method of claim 2, wherein saidseparating step is carried out by: (i) contacting said first CTLpopulation to anti-CD62L antibody, wherein said antibody is immobilizedon a solid support, so that central memory cells bind to said support;then (ii) separating said support from said CTL population with centralmemory cells bound thereto; (iii) and then separating said centralmemory cells from said solid support to produce said central memoryenriched CTL subpopulation.
 4. The method of claim 1, further comprisingthe step of concurrently administering Interleukin-15 to said subject inan amount effective to increase the proliferation of said central memoryT cells in said subject.
 5. The method of claim 1, wherein said subjectis a human subject.
 6. The method of claim 1, wherein said subject isafflicted with cancer.
 7. The method of claim 1, wherein said subject isafflicted with an infectious disease.
 8. The method of claim 1, whereinsaid subject is immunodeficient.
 9. The method of claim 1, wherein saidcentral memory-enriched T cells are modified in vitro with at least onegene that targets cancer cells.
 10. A pharmaceutical formulationconsisting essentially of an in vitro expanded primate cytotoxic Tlymphocyte (CTL) population, said CTL population enriched prior toexpansion for central memory T lymphocytes, and depleted prior toexpansion of effector memory T lymphocytes.
 11. The formulation of claim10, wherein said CTL population is produced by the process of: (a)collecting a first CTL population from a donor; (b) separating a CTLsubpopulation enriched for CD62L⁺ central memory T lymphocytes anddepleted of CD62L⁻ effector memory T lymphocytes to produce a centralmemory-enriched CTL subpopulation; (c) expanding said centralmemory-enriched CTL subpopulation in vitro in a culture medium; and then(d) collecting cells from said culture medium to produce said CTLpreparation.
 12. The formulation of claim 11, wherein said separatingstep is carried out by: (i) contacting said first CTL population toanti-CD62L antibody, wherein said antibody is immobilized on a solidsupport, so that central memory cells bind to said support; then (ii)separating said support from said CTL population with central memorycells bound thereto; (iii) and then separating said central memory cellsfrom said solid support to produce said central memory enriched CTLsubpopulation.
 13. The formulation of claim 10, wherein said centralmemory-enriched T cells are modified in vitro with at least one genethat targets cancer cells.
 14. A method of making a cytotoxic Tlymphocyte (CTL) preparation useful for adoptive immunotherapy; saidmethod comprising the steps of: (a) collecting a first CTL populationfrom a donor; (b) separating a CTL subpopulation enriched for CD62L⁺central memory T lymphocytes and depleted of CD62L⁻ effector memory Tlymphocytes to produce a central memory-enriched CTL subpopulation; (c)expanding said central memory enriched CTL subpopulation in vitro in aculture medium; and then (d) collecting cells from said culture mediumto produce said CTL preparation.
 15. The method of claim 14, whereinsaid expanding step comprises administering Interleukin-15 to saidcentral memory subpopulation in vitro.
 16. The method of claim 14,wherein said central memory-enriched T cells are modified in vitro withat least one gene that targets cancer cells.
 17. An in vitro expandedprimate cytotoxic T lymphocyte (CTL) preparation produced by the processof claim 14.